Control and security device for burners

ABSTRACT

A burner for a car heater comprises an impeller for the supply of combustion air, and further, measuring means for controlling the supply of fuel. The impeller is inserted between the flame developed in said burner and a signal detector. This detector receives light pulses of different frequencies from the flame through the rotating impeller different with the frequency depending upon the different rotational speeds of the impeller. These frequencies are transformed into signals, which are supplied to the measuring means for controlling the fuel supply to the burner in relation to the quantity of combustion air supplied. This means also that the supply of fuel is shut off if the rotation of the impeller stops or if the flame goes out.

United I States Patent [1 1 Johansson et al.

11] 3,825,397 ['45] July 23, 1974 CONTROL AND SECURITY DEVICE FOR BURNERS Inventors: Sture Ra nar Johansson, Varberg;

Hilding ke Gerry Carlsson, Skallinge, both of Sweden Assignee= MPPQFFEICEL AB, te

Sweden Filed: May 21, 1973 Appl. No.: 361,963

Foreign Application Priority Data June 15, 1972 Sweden 7869/72 US. Cl. 431/79, 431/90 Int. Cl. F23n 5/08 Field of Search 431/90, 79; 236/11 References Cited UNITED STATES PATENTS 2,870,778 1/1959 McCarty 43l/90 X Primary Examiner--William E. Wayner Attorney, Agent, or Firm-Alter Weiss Whitesel &

Laff

[5 7] ABSTRACT quantity of combustion air supplied. This means also that the supply of fuel is shut off if the rotation of the impeller stops or if the flame goes out.

4 Claims, 1 Drawing Figure CONTROL AND SECURITY DEVICE FOR BURNERS This invention relates to a control and security device for burners, especially for such burners as are used in car heaters. The device comprises a rotatable disc inserted between the burner flame and a signal detector. The rotational speed of the disc is in relation to the combustion air supplied. Holes in the disc are so arranged that, at different rotational speeds, it transforms the light from the burner flame into light pulses of different frequencies, which are supplied to the signal detector.

The term impeller is used herein to describe a fan device for moving air. The device has alternate moving blades and open spaces, whereby, as to any given spot on either side of the device, light passing through the open spaces is interrupted when the blades pass over that spot. The term impeller is used without restriction as to the angle of the blade. Therefore, it covers both propeller and impeller action.

The main object of the invention is to provide a simple device for sensing the rotational speed of the impeller and to use this sensed speed for controlling the fuel supply. This means that the mixture ratio between fuel and air can be maintained constant for all operation voltages and at the same time from the point of view of security the important function is achieved, that the fuel supply ceases if the combustion air fan stops.

In combination therewith a supervision of the flame is achieved, so that the fuel supply is shut off if the flame goes out.

According to the invention, the hole disc comprises an impeller, which supplies the combustion air to the burner. Further the signal detector is so arranged that it, in dependence of the light pulse frequencies received, controls a device for regulating the quantity of fuel supplied to the burner.

Other objects and advantages of the present invention will become apparent from consideration of the following description taken in connection with the accompanying drawing, which partly in section and partly in perspective shows a device according to the invention.

In the drawing 1 is a vaporising body inserted in a burner, the turbulence chamber and combustion chamber of which are designated 2 and 3 respectively.

By means of a dosing device, e.g., a dosing pump or a dosing magnet valve, a measured quantity of fuel is supplied to the vaporising body 1. This device is designated 4. The light from the burner flame is transmitted via a light conductor 5 with fiber optics to the one side of the impeller 7, belonging to the combustion air fan 6. On the opposite side of the impeller 7 there is a light detector .8, comprising a photo diode, a photocell, a photo resistance or the like. I

'The light from the burner flame, modulated by the impeller 7, hits the light detector 8, which thus generates alternating current. By obtaining alternatingcurrent from the light detector 8 the amplification of the signal therefrom can be made essentially simplierand above all more tolerant towards great temperature fluctuations.

The electronic section 9 controls the fuel dosing device 4 and thus the fuel supply to the vaporising body 1. It will therefore be possible tomaintain the mixture ratio between fuel and air constant for all operation voltages. At the same time the fuel supply will be shut ofi, if the flamge goes out or the rotation of the impeller ceases. t

We claim:

1. A control and security device for burners, especially such used in heaters, said device comprising an impeller means for supplying combustion supporting air to said burner, and measuring means for supplying an amount of fuel to said burner, light signal detector means, said impeller means being inserted between the flame developed in said burner and said signal detector, whereby the impeller chops the light of the flame falling on said signal detector means, said light detector being capable of receiving from said flame through said impeller light pulses at a frequency set by the rotational speed of said impeller, and means for transforming these frequencies into signals supplied to the measuring means to control the supply of fuel to said burner in relation to the combustion air supplied.

2. The device of claim 1 and light transmitting optical fiber means extending from the vicinity of the flame to one side of the impeller.

3. The device of claim 2 and said detector means comprising a photocell positioned on the opposite side of said impeller to receive light transmitted from said flame through said optical fiber.

4. The device of claim 1 wherein said impeller is a r squirrel cage blower. 

1. A control and security device for burners, especially such used in heaters, said device comprising an impeller means for supplying combustion supporting air to said burner, and measuring means for supplying an amount of fuel to said burner, light signal detector means, said impeller means being inserted between the flame developed in said burner and said signal detector, whereby the impeller chops the light of the flame falling on said signal detector means, said light detector being capable of receiving from said flame through said impeller light pulses at a frequency set by the rotational speed of said impeller, and means for transforming these frequencies into signals supplied to the measuring means to control the supply of fuel to said burner in relation to the combustion air supplied.
 2. The device of claim 1 and light transmitting optical fiber means extending from the vicinity of the flame to one side of the impeller.
 3. The device of claim 2 and said detector means comprising a photocell positioned on the opposite side of said impeller to receive light transmitted from said flame through said optical fiber.
 4. The device of claim 1 wherein said impeller is a squirrel cage blower. 